eb02z06

iTrader: (18)

Hi guys, I'm trying to make sense of how to figure the cfm of a intercooler. I'm using the #'s from Bell Intercoolers as an example. From the there site a vertical flow intercooler which is 19X8x3.5 flows 1247cfm. Then I just recently made my own vertical flow that is 25x6x3.5 and it should flow according to Bell 1689cfm.

Now this is where I get confused-if I decide to use a 25x8x3.5 core the flow goes from 1689cfm to 1647cfm even though the area is larger? Can someone explain to me how that works?

Thanks!

onfire

iTrader: (17)

Depends if it's a vertical flow or horizontal flow core. ATA IC's are a tradeoff...you try to find a balance between pressure drop and thermal eff. Vertical flows have great flow potential since they have more flow channels, but the thermal eff is poor due to the short length of the flow channels. Horizontal flow cores have much better thermal eff, but the pressure drop is higher. CFM doesn't really mean anything unless a pressure drop is referenced to the flow. 1700cfm at 1.5" of drop is great. 2000cfm at 5 " of drop is not so great.

eb02z06

iTrader: (18)

No pressure drop is given on the site-the cores are vertical flow like in the pic.

Lonnies Performance

iTrader: (16)

If you look at the width, it determines the number of internal passages. Therefore the wider it is, the more it flows.

The next would be the length. As the intercooler gets longer, it also cools better due to the air being in the intercooler longer to transfer heat. Unfortunately, the longer the path, the more frictional losses that occur & therefore the less it flows. It looks like you lose about 2.5% flow with 2 inches of additional length in your situation, but gain 33% cooling area. This is not necessarily 33% additional cooling, since as the charge air cools, it transfers less heat to the intercooler.

Based on this, the widest intercooler is best. Now if you could make the 8" lg intercooler about 3/4" wider by adding 1 more row of tubes, you will regain your flow loss.

eb02z06

iTrader: (18)

Now I get it! Thanks buddy!!!

onfire

iTrader: (17)

Keep in mind that on a vertical flow IC, adding an inch or two to intercooler width to a 24 inch wide core will have very little effect on thermal eff. Length is dominant for thermal eff on a vertical flow core. A 6" flow length core isn't going to drop much heat on a high boost set-up....been there done that. If I was using a core like your above pic, meth would be a necessity for high boost.

eb02z06

iTrader: (18)

Thanks for your input bro-it all makes perfect sense now. I will go with a 28"x8"x3.5" core. Does anyone else besides Bell make cores?

usd2sing

iTrader: (15)

clarification pls?

if the i/c is to small (assuming), and u up the boost level is there any issues other than heat?
like limiting flow/boost levels because the i/c isnt big enough.
thanks

camarols1

iTrader: (17)

Yes, the under-sized intercooler becomes the cork in the system.
The turbo or blower will have to work extra hard to overcome the restriction.

DeltaT

iTrader: (5)

This is all layed out well (and a lot more), with equations and diagrams, in Corky Bell's (of Bell Intercoolers) book 'Maximum Boost' (for turbos) and 'Supercharged'. Highly recommended although there are a few typos in the equations in the supercharged book.

Jim

eb02z06

iTrader: (18)

Okay-now i'm getting a bit confused. My current cooler is 19"wx8"Hx3.5D" deep, the cooler I made is 25"wx6"Hx3.5"D. According to Bell the 19x8 only flows a bit over 1200 cfm and the 25x6 flows over 1650cfm but your saying that a 25x8 will be better? I can see how the 8" hi is better but what your not seeing is that half of the intercooler is covered by a non-flow area on the C5. I would think say for example a 28.5x6 would be better than a 28.5x8 but if your not getting much flow over it does it still really matter? A 28.5x6x3.5 will be smaller more compat and i can get more elaborate with the end tanks to help direct flow better?

Here is a pic of the current cooler-by using the the mounting brackets as a guage you can see that only about half of the 8" core is exposed to incoming air? I would think a 6" core would be more effecient. FWIW-with meth and the current cooler I can keep temps under 100 degrees with meth on hot summer day going down the track-BUT I think theres is probably at least 2-4 psi of boost loss through the cooler.

eb02z06

iTrader: (18)

FWIW-the TTIx twin turbo kits for C5's which I have seen make over 900 rwhp use a intercooler core of 27Wx6Hx3.5D-mounted infront of the rad in a C5 and it does a very good job of keeping IAT temps down. Wouldn't a turbo run hotter than a blower?